This invention relates generally to fiber optic angular rate sensors and, more particularly, to a fiber optic angular rate sensor arrangement whereby common mode noise is minimized.
The most significant sources of noise in the output of a fiber optic angular rate sensor (gyroscope) are common mode noise (CMN) and shot noise. Shot noise is generated in photodetectors included in the system and is proportional to the square root of the light power at the input to the photodetectors.
Common mode noise has a major component which is a light source intensity noise. It is proportional to the light power and when the light power to the photodetectors exceeds approximately ten .mu.W, common mode noise is the most significant component of the total noise in the sensor output.
Common mode noise minimization is achieved by the present invention.